Multi-Rotational Indexer

ABSTRACT

An indexing device for flow control includes a first cylinder having a plurality of slots disposed thereon along a path that changes rotational direction at least once before the path completes a circle around the first cylinder; and a second cylindrical member forming a concentric assembly with the first cylinder, such that an index pin disposed on the second cylindrical member is configured to move in the plurality of slots on the first cylinder when the first cylinder and the second cylindrical member move relative to each other.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates generally to a rotational indexing systemused in a flow control valve.

2. Background Art

The economic climate of the petroleum industry demands that oilcompanies continually improve their recovery systems to produce oil andgas more efficiently and economically from sources that are becomingincreasingly difficult to exploit without increasing the cost to theconsumer. One successful technique currently employed is the drilling ofdeviated wells, in which a number of horizontal wells are drilled from acentral vertical borehole. In such wells, and in standard verticalwells, the well may pass through various hydrocarbon bearing zones ormay extend through a single zone for a long distance. One method toincrease the production of the well is to perforate the well in a numberof different locations, either in the same hydrocarbon bearing zone orin different hydrocarbon bearing zones, and thereby increase the flow ofhydrocarbons into the well.

One problem associated with producing from a well in this manner relatesto the control of the flow of fluids from the well and to the managementof the reservoir. For example, in a well producing from a number ofseparate zones (or from laterals in a multilateral well) in which onezone has a higher pressure than another zone, the higher pressure zonemay disembogue into the lower pressure zone rather than to the surface.Similarly, in a horizontal well that extends through a single zone,perforations near the “heel” of the well, i.e., nearer the surface, maybegin to produce water before those perforations near the “toe” of thewell. The production of water near the heel reduces the overallproduction from the well.

A manner of alleviating this problem is to insert a production tubinginto the well, isolate each of the perforations or laterals withpackers, and control the flow of fluids into or through the tubing.However, typical flow control systems provide for either on or off flowcontrol with no provision for throttling of the flow. To fully controlthe reservoir and flow as needed to alleviate the above describedproblem, the flow is throttled. A number of devices have been developedor suggested to provide this throttling although each has certaindrawbacks. Note that throttling may also be desired in wells having asingle perforated production zone.

For example, U.S. Pat. No. 6,722,439 issued to Garay et al. disclosesmulti-positioned sliding sleeve valve that is operable in a plurality ofpositions including fully open, fully closed, and positions in between.The valve uses a hydraulic control system to move the sliding sleeve apredetermined amount for a given applied control pressure. Similarly,U.S. Pat. No. 6,973,974 issued to McLoughlin et al. discloses valves foruse in wells. A valve disclosed in this patent includes a choke having aplurality of orifices to allow variable flow control.

When a valve having multiple positions are used downhole, an indexingdevice (or indexer) is often used to provide control and indication ofthe various opening states. Example of indexing devices may be found,for example, in U.S. Pat. No. 6,973,974 issued to McLoughlin et al. andU.S. Pat. No. 6,948,561 issued to Myron. An indexing device typicallycomprises a pin movable in a series of slots (typically, J-shaped slotsor J-slots). A piston restrained to move longitudinally engages androtates an index sleeve to allow the pin to advance into the next J-slottrack. Each slot determines the position of the valve.

Existing indexing apparatus uses a plurality of J-slots arranged aroundthe circumference of a tubing to provide the multiple control positions.However, such a design limits the number of positions that can beobtained.

SUMMARY OF INVENTION

In one aspect, embodiments of the invention relate to indexing devicesfor flow control. An indexing device in accordance with one embodimentof the invention includes a first cylinder having a plurality of slotsdisposed thereon along a path that changes rotational direction at leastonce before the path completes a circle around the first cylinder; and asecond cylindrical member forming a concentric assembly with the firstcylinder, such that an index pin disposed on the second cylindricalmember is configured to move in the plurality of slots on the firstcylinder when the first cylinder and the second cylindrical member moverelative to each other.

Another aspect of the invention relate to flow control valves. A flowcontrol valve in accordance with one embodiment of the inventionincludes an indexing device, wherein the indexing device includes afirst cylinder having a plurality of slots disposed thereon along a paththat changes rotational direction at least once before the pathcompletes a circle around the first cylinder; and a second cylindricalmember forming a concentric assembly with the first cylinder, such thatan index pin disposed on the second cylindrical member is configured tomove in the plurality of slots on the first cylinder when the firstcylinder and the second cylindrical member move relative to each other,wherein the plurality of slots correspond to a plurality of openingconditions of the flow control valve.

Another aspect of the invention relate to methods for controlling fluidflow downhole. A method in accordance with one embodiment of theinvention includes disposing a flow control valve in a wellbore, whereinthe flow control valve is equipped with an indexing device includes afirst cylinder having a plurality of slots disposed thereon along a paththat changes rotational direction at least once before the pathcompletes a circle around the first cylinder; and a second cylindricalmember forming a concentric assembly with the first cylinder, such thatan index pin disposed on the second cylindrical member is configured tomove in the plurality of slots on the first cylinder when the firstcylinder and the second cylindrical member move relative to each other,wherein the plurality of slots correspond to a plurality of openingconditions of the flow control valve; and moving the index pin to one ofthe plurality of slots to change an opening condition of the flowcontrol valve.

Other aspects and advantages of the invention will become apparent fromthe following description and attached claims.

BRIEF SUMMARY OF DRAWINGS

FIG. 1 shows a system for pumping fluid from a wellbore that may be usedwith embodiments of the invention.

FIGS. 2A and 2B show a conventional indexer used in controlling valvesdownhole.

FIGS. 3A and 3B show a pattern of J slots on a conventional indexer.

FIGS. 4A and 4B show slots of an indexer in accordance with oneembodiment of the invention.

FIGS. 5A-5C show examples of paths (arrangements) of slots on indexersin accordance with embodiments of the invention.

DETAILED DESCRIPTION

Embodiments of the invention relate to indexing devices for use in flowcontrol in downhole applications. In the following description, numerousdetails are set forth to provide an understanding of the presentinvention. However, it will be understood by those skilled in the artthat the present invention may be practiced without these details andthat numerous variations or modifications from the described embodimentsmay be possible.

Referring to FIG. 1, a system 20 for producing fluids from a wellbore 22to the surface 24 is featured. In the illustrated embodiment, system 20includes an electric submersible pumping system (ESP) 26, productiontubing 28, a fluid intake valve assembly 30, a hydraulic control line32, a hydraulic controller 34, a first packer 36, and a second packer38. However, a pumping system need not be used. Fluid pressure may besufficient to produce fluid to the surface without the use of a pumpingsystem. As an additional measure, wellbore 22 is lined with casing 40.

In the illustrated embodiment, valve assembly 30 is disposed in ahorizontal deviation 41 of wellbore 22. Valve assembly 30 is used tocontrol the intake of fluid into system 20. Fluids, as referenced byarrows 42, flow from a geological formation 44 through perforations 46in casing 40 into wellbore 22. First packer 36 and second packer 38define a first region 48 within wellbore 22. Fluid 42 is drawn intosystem 20 from first region 48 through inlet ports 50 in valve assembly30.

Valve assembly 30 is operable to control the size of the area thoughwhich fluid 42 may flow into valve assembly 30. In the illustratedembodiment, valve assembly 30 is operated by hydraulic pressurecontrolled from the surface 24 by a hydraulic controller 34. A controlline 32 is used to apply hydraulic pressure to valve assembly 30 fromhydraulic controller 34. Hydraulic controller 34 may be as simple as apair of manually operated valves or as complex as a computer controlledsystem. See U.S. Pat. No. 6,973,974 issued to McLoughlin et al., whichis assigned to the present assignee and is incorporated by reference inits entirety.

Multi-position valves typically are used with indexing devices(indexers) to control and indicate the various opening positions of thevalves. Conventional indexing devices use J-slots arranged around thecircumference of the tube shaped devices to indicate the variouspositions of the valves, as illustrated in FIGS. 2A-2C.

FIG. 2A shows a conventional indexer 134 assembled in a housing 66. FIG.2B shows the indexer 134 separated from the housing 66. As shown in FIG.2B, indexer 134 includes J-slots 176 that are arranged around thecircumference of the indexer 134. The housing 66 includes a pin 178 thattravels in the J-slots 176. In an alternative embodiment, an indexer maybe the outer member, while the pin is disposed on an inner member. Therelative movement of the housing 66 with respect to the indexer 134determines which J slot the pin 178 is in, which in turn controls thevalve positions. The movement of the housing 66 relative to the indexer134 may be controlled by a controller (shown as 34 in FIG. 1) mediatedby a control line (shown as 32 in FIG. 1). Typically, such control ismediated by hydraulics that drives a piston, which may be linked,directly or indirectly, to the indexer 134 or the housing 66. As thepiston is driven up or down, the relative movement between the housing66 and the indexer 134 will be guided by indexer pin 178 acting onJ-slot 176 of indexer 134.

J-slots 176 and indexer pin 178 cause indexer 134 to rotate about itsaxis, thereby the valve assembly is shifted from one position to thenext. Indexer 134 makes one complete revolution as valve assembly 30transits from the closed position to the fully open position and back tothe closed position. In some conventional indexers, a portion of theouter surface 180 of indexer 134 may be configured with a toothedsurface 182. A latch 184, secured to indexer housing 66, may be usedwith toothed surface 182 to ensure that indexer 134 rotates about itsaxis in only one direction. This ensures that J-slot 176 cooperates withindexer pin 178 to produce the desired motion of indexer 134.

The indexing device (or indexer) 134 in FIG. 2B has a plurality of Jslots 176 arranged around the circumference of the tube in a spiralpath. A “path” as used herein refers to an imaginary line that connectsthe bottom portions of the J slots. In this configuration, the beginningand the end of the spiral path may be connected by a longitudinal (alongthe axis direction of the tube-shaped indexer) slot (not shown) suchthat the pin 178 can come back to the beginning when it rotates around acomplete circumference. When the J slots 176 are arranged in a spiralpath, as shown in FIG. 2B, the “height” (from the top to the bottom ofeach “J”) of each J slot may be the same.

A alternative configuration of an indexer may have the J slots 176arranged around the circumference of the indexer without the spiralpath, i.e., in a circle around the indexer at the same longitudinallocation, as shown in FIG. 3A. FIG. 3B shows the indexing sleeve of FIG.3A opened up into a flat sheet to illustrate the arrangement of the Jslots 176. In this alternative configuration, the “height” of each Jslot may be different such that when an indexer pin 178 rests againstthe “top” (closed end) of the J slot, the axial location of the indexerpin 178 has a correlation with its rotation position.

As shown in FIG. 3B, the axial locations (z1, z2, . . . zn) of theclosed ends of the J slots directly correlate with the rotational(azimuthal) locations (x1, x2, . . . xn) of the slots. This relationshipcan be maintained whether the J slots are arranged on a spiral path (asshown in FIG. 2B) or a non-spiral path (as shown in FIG. 3B). With thisrelationship, knowledge of the axial location of the indexer pin (shownas 178 in FIG. 2A) can provide the rotational (azimuthal) location ofthe indexer pin, and vice versa. That is, the axial locations (zi) of anindexer pin is indexed by the rotational (azimuthal) location (xi) ofthe indexer pin. Therefore, if the axial locations of the indexer pincorrespond to different openings of a valve (e.g., a sliding valve),then one can obtain this information from the rotational locations ofthe indexer pin, and vice versa.

As illustrated in FIG. 3B, the number of J slots in an indexerdetermines how many opening positions a valve can be operated. Since thecircumference is limited by the diameter of the indexer 134, the widthof the slots determines how many J slots 176 may be provided in theindexer. The width of the slots in turn is determined by the indexingpin 178 that travels in these slots. For reliable operation, theindexing pin 178 needs to withstand significant impact forces withoutbreaking. Therefore, the indexing pin 178 cannot be made too thin. As aresult, the number of J slots 176 around a fixed circumference is oftenlimited.

Embodiments of the invention provide indexers that can have more slots(J-shaped slots or other-shaped slots) than the conventional indexersbecause the slots of an indexer of the invention are not arranged in afashion that is limited by the circumference. For example, in accordancewith embodiments of the invention, the slots may be arranged in a paththat reverses its rotational (azimuthal) direction before finishing acomplete circle around the circumference. Such indexers may be referredto as “multi-rotational” indexers.

As shown in FIG. 4A and FIG. 4B, an indexer 400 of the invention mayinclude a plurality of slots (grooves) 402 or other appropriate shapedgrooves. As shown in FIG. 4B, the plurality of slots 402 are disposedalong a path that forms a closed loop on the circumference of theindexer. This closed loop path is more clearly illustrated in FIG. 5A.An indexer pin traveling along the closed loop path shown in FIG. 5Awill change its rotational (azimuthal) direction before it completes acircle around an indexer. That is, the indexer pin will not travel in asingle rotational direction. Instead, it will reverse its rotationaldirection at least once. This closed loop path has a length that islonger than the circumference of the indexer, making it possible to havemore slots included on the indexer. Other examples of closed loop pathsthat may provide more slots on an indexer in accordance with embodimentsof the invention are shown in FIGS. 5B-5C. One of ordinary skill in theart would appreciate that these examples are for illustration only andother modifications are possible without departing from the scope of theinvention.

An indexer of the invention may be used with a housing having an indexerpin as shown in FIG. 2A. In an alternative embodiment, an indexer of theinvention may be used with an inner member having an indexer pindisposed inside the indexer. In the latter case, the inner member may bea sleeve, a hollow cylinder, or a solid cylinder. The relative movementbetween the indexer and the outer housing or the inner member determinesthe various openings of a valve. Indexers of the invention may be usedwith any downhole valves that need to be operated in multiple openingpositions. Such valves, for example, include a pressure-actuatedcirculation valve, a flow-actuated circulation valve, and a differentialvalve.

Advantages of the current invention include one or more of thefollowing. An indexer of the invention may have any number of indexgrooves (or slots) for finer flow control, not limited by thecircumference of the indexing device. Additionally, the reversal ofrotational direction of the slots may allow multiple gradational openingand closing of flow control valves in traversing the full circumferenceof the indexing sleeve.

While the invention has been described with respect to a limited numberof embodiments, those skilled in the art will appreciate that otherembodiments can be devised which do not depart from the scope of theinvention as disclosed herein. Accordingly, the scope of the inventionshould be limited only by the attached claims.

1. An indexing device for flow control, comprising: a first cylinder having a plurality of slots disposed thereon along a path that changes rotational direction at least once before the path completes a circle around the first cylinder; and a second cylindrical member forming a concentric assembly with the first cylinder, such that an index pin disposed on the second cylindrical member is configured to move in the plurality of slots on the first cylinder when the first cylinder and the second cylindrical member move relative to each other.
 2. The indexing device of claim 1, wherein the second cylindrical member forms an outer cylinder of the concentric assembly.
 3. The indexing device of claim 1, wherein the second cylindrical member forms an inner member of the concentric assembly.
 4. The indexing device of claim 1, wherein the indexing device is connected to a control line that controls relative movement between the first cylinder and the second cylindrical member.
 5. The indexing device of claim 1, wherein the plurality of slots are J-shaped slots.
 6. A flow control valve having an indexing device, wherein the indexing device comprises: changes rotational direction at least once before the path completes a circle around the first cylinder; and a second cylindrical member forming a concentric assembly with the first cylinder, such that an index pin disposed on the second cylindrical member is configured to move in the plurality of slots on the first cylinder when the first cylinder and the second cylindrical member move relative to each other, wherein the plurality of the slots correspond to a plurality of opening conditions of the flow control valve.
 7. The flow control valve of claim 6, wherein the flow control valve is at least one selected from a pressure-actuated circulation valve, a flow-actuated circulation value, and a differential valve.
 8. The flow control valve of claim 6, wherein the plurality of slots are J-shaped slots.
 9. The flow control valve of claim 6, further comprising a control line configured to control the indexing device.
 10. The flow control valve of claim 6, wherein the second cylindrical member forms an outer cylinder of the concentric assembly.
 11. The flow control valve of claim 6, wherein the second cylindrical member forms an inner member of the concentric assembly.
 12. A method for controlling fluid flow downhole, comprising: disposing a flow control valve in a wellbore, wherein the flow control valve is equipped with an indexing device comprising: a first cylinder having a plurality of slots disposed thereon along a path that changes rotational direction at least once before the path completes a circle around the first cylinder; and a second cylindrical member forming a concentric assembly with the first cylinder, such that an index pin disposed on the second cylindrical member is configured to move in the plurality of slots on the first cylinder when the first cylinder and the second cylindrical member move relative to each other, wherein the plurality of slots correspond to a plurality of opening conditions of the flow control valve; and moving the index pin to one of the plurality of slots to change an opening condition of the flow control valve.
 13. The method of claim 12, wherein the moving the index pin is performed through a control line connected to the flow control valve.
 14. The method of claim 12, wherein the plurality of slots are J-shaped slots.
 15. The method of claim 12, wherein the flow control valve is at least one selected from a pressure-actuated circulation valve, a flow-actuated circulation valve, and a differential valve.
 16. The method of claim 12, wherein the second cylindrical member forms an outer cylinder of the concentric assembly.
 17. The method of claim 12, wherein the second cylindrical member forms an inner member of the concentric assembly. 